Manipal Engineering Manipal Engineering Solved Paper-2010

  • question_answer
    A freshly prepared radioactive source of half-life 2 h emits radiation of intensity which is 64 times the permissible safe level. Calculate the minimum time after which it would be possible to work safely with this source.

    A)  12 h                                      

    B)  24 h

    C)  6 h                        

    D)         130 h

    Correct Answer: A

    Solution :

    For working safely, the activity must reduce to\[\frac{1}{64}\].                 \[\frac{N}{{{N}_{0}}}={{\left( \frac{1}{2} \right)}^{n}}=\frac{1}{64}\] \[\therefore \]  \[n=6\] Thus,     \[t=nT=6\times 2=12\,\,h\]


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